Carbon for electrotechnical uses and process of manufacture thereof



Nov. 25, 1930. M, Q WALD 1,783,135

CARBON FOR ELECTRO TECHNICAL USES AND PROCESS OF MANUFACTURE THEREOF Filed May 24, 1928 Patented Nov. 25 1930 UNITED STATES PATENT. OFFICE MARGEL OSWALD, OF NANTERRE, FRANCE, ASSIGNOR TO COMPAGNIE LORRAINE DE CHABBONS POUR LELEC'IRIGITE, OF PARIS, FRANCE, A CORPORATION 'OF FRANCE cannon FOR ELECTROTECHNICAL ses AND raooessor' mnuracrmm 'rnnnnor Application filed May 24, 1928, Serial No. 280,362, and in France April 8, 1927.

' 5 pensive andwhich can be used with perfect safety, are adapted to serve as substitutes for carbons to be connected electrically with a metal in all cases where the connection .is usually effected by setting the carbon in a metallic mount, by surface metallization or otherwise, with greater ease-of attachment and certainty of. intimate contact at the points of connection. With the use of these carbons -it is possible to dispense with the employment of separate metallic elements to be connected to the carbon, there being substituted therefor av simple metallic covering or coating applied in manner'hereinafter de scribed.

low with reference to the accompanying drawing the simple case of the preparation of cylindrical carbon pads.

Fig. 1 is a perspective view partly crosshatched showing a rod of carbon which has been freshly moulded, and not yet notched.

Fig. 2 is a like view showing the carbon rod notched or scored transversely.

Fig. 3 is a perspective view ,of a piece of the carbon rod after hardening and afterrupture.

Fig. 4 is a section on the line .IVIV of The soft carbon rod a resulting from amoulding operation or'after passage through a draw plate (Fig. 1) is, notched circularly at 1), b b b b, to a depth which con-- stitutes a small fraction of its diameter (Fig. 2). The notches b are cut in parallel planes and at distances apart such that two consecutive notches b b are so spaced that the intermediate body is about equal in volume to that of a finished carbon element A.

The long carbon rod thus notched having been allowed to harden, rupture is efiected by application of a relatively slight effort at the notched points 6, 6 6 ,12 6 c It is known that after hardening the carbon is of the same geometrical form as in the raw state and that with but slight shrinking it is-of substantially the same dimensions.

The rupture results in the formation of carbon elements A having end faces B each including a smooth annular region cat the part where the notch was made in the carbon rod when soft, and a central rugose or rough surface 03 particularly adapted to receive a metallic coating.

It is evident that the process described is applicable, mutatis mutandis, what ever be the form of the carbon element and that it may be applied to materials other than carbon in which case it suffices tocut in the cara soft state, notches, scores, or incisions which facilitate rupture after hardening, leaving at the faces where the rupture is made one .or several central rough regions each bounded by a narrow smooth region where the notch or the like was formed.

These rough parts are then covered with an adherent metallic covering by the aid of any known process such as electrolysis, abrasion,'pulverization, chemical precipitation, cathodic bombardment and so on.

' In utilizing the electrolytic process for example it suflices to connect the carbon to the cathode in. an electrolytic bath to deposit on the carbon metal from the bath. If abrasion is resorted to, the rough carbon surface is rubbed vigorously on a mass of the metal which is to be fixed to the carbon. Pulverization is preferably effected by a spraying process employing a pistol. Chem-. ical precipitation may be effected in manner similar to that adopted for chemical silvering. Cathodic bombardment is referred to as an alternative which is hardly suificiently economical to be utilized in practice.

' The advantages of the new process reside in the simplicity and ease of manufacture on a large scale and also in the economy which results from dispensing with the moulding of separate sections of carbon, and from the replacement by a cheap metallic coating or covering which can be easily and readily effected of the special and expensive metallic pieces such as caps, straps, terminals, plates etc. heretofore used.

Among the possible applications of the invention there may be mentioned by way of example 1. The mounting of anodes for batteries. In the use of the improved carbons it is unnecessary to observe strict tolerances with regard to diametral dimensions of the an- 0 es.

2. The mounting of cylindrical brushes with copperized heads for magnetos or small universal motors.

3. Theconnection of the rods of carbon or carborundum as resistance electrodes of are or electrical furnaces.

The invention also lends itself to the employment of complex metallic coverings comprising difl'erent metals juxtaposed or superposed. In this case the several metal coatings are applied successively to the parts of the carbon which are to receive the metal.

The rough parts obtained in the manner described are also adapted to receive nonmetallic coverings which may or may not be colloidal, for example, such as employed in the battery and accumulator industry. In the application of such coverings it is preferable to use the pulverization process which projects a solution in the form of fine drops by means of a compressed air or gas What I claim is The method of making carbon conductors metallized on the end, comprising, grooving circumferentially a carbon rod while soft, at length intervals equal to the desired lengths of the conductors, breaking the rod in the planes of the grooves provlding the conductors thus separated, with rough end surfaces of fracture, bounded by the smoother walls of the said grooves, and metallizing the said surfaces of fracture.

In testimony whereof, I have aflixed my signature.

MARCEL OSWALD. 

